Find the Last Matching Index in Python

Introduction

In Python, we can use a list comprehension and enumerate() to find the index of the last element in a list that satisfies a given condition. This challenge will test your ability to use these tools to solve a problem.

Skills Graph

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Find the Last Matching Index

Write a function find_last_index(lst, fn) that takes a list lst and a function fn as arguments. The function should return the index of the last element in lst for which fn returns True. If no element satisfies the condition, the function should return -1.

def find_last_index(lst, fn):
  return len(lst) - 1 - next(i for i, x in enumerate(lst[::-1]) if fn(x))

find_last_index([1, 2, 3, 4], lambda n: n % 2 == 1) ## 2

Summary

In this challenge, you learned how to use a list comprehension and enumerate() to find the index of the last element in a list that satisfies a given condition. This is a useful technique to have in your Python toolbox!

Find the Last Matching Index

Introduction

Skills Graph

Find the Last Matching Index

Summary

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